Internal thread gauge



INTERNAL THREAD GAUGE Filed Feb. e.. 1939 ATTORNEY mesh therewith.

Patented July l5, 1941 stanley G. Johnson, Hartford, conn., ossignor toNiles-Bement-Pond Company, Hartford, Conn., a corporation of New JerseyApplication February 8, 1939, Serial No. 255,281-

claims (cia3-19s) j 1 'Ihis invention relates to internal thread gaugesand particularly to a gauge of this -ty'pe that `is inexpensive to makeand which may be used to quickly indicate variations in dimensions ofinternal screw threads from a given standard to a high degree ofprecision.

.An object of the present invention'is to provide a telescoping rodadapted to fit within a member which has internal screw threads beinggauged, there being vthread engaging members at opposite ends oi the rodnormally forced into engaging contact with the threads being gauged.

A feature oi' importance of the invention is that-the thread engagingmembers are freely rotatable and having cylindrical surfaces grooved tocorrespond to the pitch of the screw threads being gauged so that theymay properly inter- Another object of importance posedabutments formed.or mounted upon intermediate portions of the' rod which are spaced.

apart when the thread contacting members are in engagement with thescrew threads being gauged, thus" enabling a measuring block to =beinserted between the abutments to determine variations in distancebetween the ends of the gauge and variations in sizes of the piecesbeing gauged.

Another feature of importance is that a spring housed within one memberand engaging the end lof a projection on the othermember of the rodnormally forces the two parts of the telescoping rod to theirmaximumdistance apart, there being 'a limiting member which prevents completeseparation Iof the two members.

With the above and other objects in view, the invention may include-thefeatures of construc-E tion and operation set forth in the followingspeciiicationand illustrated in the accompanying drawing.

In the accompanying drawing annexed hereto and forming a part of thisspecification, I have is to provide op-` Fig. 2 is a longitudinal view,partly in section, t

' and at a right angle of the -gauge shown in Fig. 1.

" invention.

In the above mentioned drawing there has beenshown but one embodiment ofthe invention which is now deemed lpreferable, but iteis to beunderstood that changes and modications may be made within the scope ofthe appended claims without departing from the spirit of the Briefly andin interiitting and telescoping members, one of which has a projectionentering an axial recess f in the other mentber'; seconda springinserted within the recessand adapted to bear against the end of theprojection; third, means to prevent separation of 'and maintain the twomem- Y bers-forming the gauging rod in 'a'.linement,v this membercomprising a small stud threadedsinto the projection and extendingthrough a .slot inv the recessed member; and fourth, opposed abut-,cured' in fixed position within and outstanding from the' projection I3enters'andslides within a, recess I6 provided therefor in the member I0.

' By meansof this stud I5 andthe recess I6 the shown the inventionembodied in a gauge for screw threads of large diameterH-but it will beunderstood that `the kinvention can be otherwise 'embodied and that thedrawing is not to be con- `strued as deilninglor limiting-the scope ofthe invention, the claims appended to this specification being reliedupon for thatpurposen In the drawing: Figure 1 is a longitudinal outsideview of a complete gauge shown 1n engaging position and with a gaugeblock inserted between abutments thereon. and

members I0 and Il are prevented from becoming separated and are alsomaintained accurately in alinement.

4On the outer end of., each member I0 and I i y members i9, adapted tollt the screw threads W being gauged, are rotatably mounted. Thesegauging members I0, as shown, are of cylindrical form having spacedannular grooves therein corresponding'to the pitch and form of the screwthreads W being gauged. lIn order to vary the dimensions or adjust theVsize of the "gauge of .55 the type shown itt-the drawing, thejgaugingits broadest aspect, the invene tion may comprise: First, a rodfmade upof two of these members is in members I9 are mounted on portions of thesleeves 20 eccentric relative to their supporting surfaces in the yokemember I1. By rotating at sleeve 20 and securing it invadjusted rotativeposition by means of a screw I8 or other means the gauging member I9 maybe moved slightly axially of the rod l0. r

On adjacent portions of the members III and I I forming the telescopingrod are small abutments 2| carefully surfaced upon their outer ends sothat they are precisely parallel to each other. Between the surfaces ofAthese abutments 2l when obtained when the gauge isl inserted within amaster gauge the correctness Vof the screw threads gauged may bedetermined.

What I 'claim is: 1. A gauge for internal screw threads comprising incombination, a two-part telescoping4 rod having a thread engaging memberat the outer end 'of each part, spring means normally forcing said partsto engage said members with the the gauge is in position as indicated inFig. 1 la gauging block` 22 having opposite parallel faces may beinserted. 'Ihis gauging block 22 may have a plurality of surfaces alongportions of one ledge or side at slightly different distances from theopposite side or edge. The gauge block 22 therefore may be placedbetween the abutments 2| and the particular surface of the gauging blockthat will pass between the abutments will indicate the distance apart ofthe gauging members I9.

It will be understood that the recessed members I0 for gauges of alldimensions may be identical and that the members II having theprojecthreads being measured, and an abutment on each of said parts ofsaid rod spaced apart when said parts are in gauging position, wherebythe adjustment of said members when in engaging positions may bedetermined.

2. `A gauge for internal screw threads comprising in combination, atwo-part telescoping rod having a thread engaging Vmember at the outerend of each part, spring means normally forcing said partsto engage saidmembers with'the threads being measured, an abutment on each of saidparts ofv said rod spaced apart when said parts are in' gaugingposition. and means contactlng said abutments to determine variations inthe distance between said abutments vwhen saidv parts are in theirengaging positions.l

3. A gauge for internal screw threads comprising-in combination, atwo-part telescoping rod screws or other fastening devices. Whenassembled Ithe rotatable gauging members Il will have their axes exactlyparallel to each other and the distance between them will be chosen toenable the gauge to be used for a particular "size of screw threadsbeing gauged. The members Il and II, when the gauge is being used. areiirst forced together and the gauge inserted within the threadedmember'W being gauged. The members I0 and Il are then separated by thespring I2, thus -forcing the gauging members Il intof work engaging'`positions. A gauge block 22 is then inserted between the abutnents 2iand the dimension ofthetblock 22 at the portion 'closely 59.

fitting between the abutments is observed. From this dimension and bycomparing the dimensions having rotatable cylindrical thread engagingmembers circumferentially grooved to intermh with the screw threadsbeing gauged at the outer endof-each part, means normally forcing said`parts to engage said members with the threads being measured, and anabutment on each of saidparts of said rod spaced apart when said partsare in gauging position, whereby the adjustment of said members A,whenin engaging positions may be determined.

4. A gauge for internal screw threads comprising in combination. atwo-part telescoping rod havingr a thread engaging member at the outerend of each part, spring means normally forcing said parts to engagesaid members-with the threads being measured,an abutment on each of saidparts of said rod spaced apart when said .parts are in gauging position,and a member having a plurality of parallel surfaces predetermineddistances apart contacting said abutments to determine variations in thedistance between said abutments` when said parts are in their engagingpositions.

- v A STANLEY G. JOHNSON.

